Re: Add support for the Win32 hook prologue (try 3)

Re: Add support for the Win32 hook prologue (try 3)

[Ross Ridge]

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Stefan Dösinger writes:
>On a partly related topic, I think the Win64 ABI requires that the first
>function is two bytes long, and there at least 6 bytes of slack before
>the function. Does gcc implement that?

As far as I can tell the Win64 ABI doesn't have either of these
requirements.  Microsoft's compiler certainly doesn't guarantee that
functions begin with two byte instructions, and the "x64 Software
Conventions" document gives examples of prologues with larger initial
instructions:

	http://msdn.microsoft.com/en-us/library/tawsa7cb(VS.80).aspx

Mind you, last I checked, GCC didn't actually follow the ABI requirements
for prologues and epilogues given in the link above, but that only breaks
ABI unwinding.

					Ross Ridge

Re: Add support for the Win32 hook prologue (try 3)

[Kai Tietz]

2009/9/11 Ross Ridge <rridge@csclub.uwaterloo.ca>:
> Stefan Dösinger writes:
>>On a partly related topic, I think the Win64 ABI requires that the first
>>function is two bytes long, and there at least 6 bytes of slack before
>>the function. Does gcc implement that?
>
> As far as I can tell the Win64 ABI doesn't have either of these
> requirements.  Microsoft's compiler certainly doesn't guarantee that
> functions begin with two byte instructions, and the "x64 Software
> Conventions" document gives examples of prologues with larger initial
> instructions:
>
>        http://msdn.microsoft.com/en-us/library/tawsa7cb(VS.80).aspx
>
> Mind you, last I checked, GCC didn't actually follow the ABI requirements
> for prologues and epilogues given in the link above, but that only breaks
> ABI unwinding.

Right, but even unwinding is still possible on x64 (so we don't break
the SEH2 unwinding support actually), as everything gcc does here in
prologue, can be expressed by chaininfo (if prologue size is bigger
then 255 bytes).



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